1. Field of the Invention
The present invention relates to compounds and compositions that are p38 MAPK inhibitors, and which are useful as anti-inflammatory agents in the treatment of, inter alia, diseases of the respiratory tract. The present invention further relates to methods for the treatment and/or prevention of certain diseases and conditions by administering such a compound.
2. Discussion of the Background
Mitogen activated protein kinases (MAPK) constitute a family of proline-directed serine/threonine kinases that activate their substrates by dual phosphorylation. There are four known human isoforms of p38 MAP kinase, p38α, p38β, p38γ, and p38δ. The p38 kinases, which are also known as cytokine suppressive anti-inflammatory drug binding proteins (CSBP), stress activated protein kinases (SAPK) and RK, are responsible for phosphorylating (Stein et al., Ann. Rep. Med. Chem., 1996, 31, 289-298, which is incorporated herein by reference in its entirety) and activating transcription factors (such as ATF-2, MAX, CHOP and C/ERPb) as well as other kinases (such as MAPKAP-K2/3 or MK2/3), and are themselves activated by physical and chemical stress (e.g. UV, osmotic stress), pro-inflammatory cytokines and bacterial lipopolysaccharide (LPS) (see Herlaar E. & Brown Z., Molecular Medicine Today, 1999, 5, 439-447, which is incorporated herein by reference in its entirety). The products of p38 phosphorylation have been shown to mediate the production of inflammatory cytokines, including tumor necrosis factor alpha (TNF α) and interleukin-(IL)-1, and cyclooxygenase-2 (COX-2). IL-1 and TNFα are also known to stimulate the production of other proinflammatory cytokines such as IL-6 and IL-8.
IL-1 and TNFα are biological substances produced by a variety of cells, such as monocytes or macrophages. IL-1 has been demonstrated to mediate a variety of biological activities thought to be important in immunoregulation and other physiological conditions such as inflammation (see, e.g. Dinarello et al., Rev. Infect. Disease, 1984, 6, 51, which is incorporated herein by reference in its entirety). Excessive or unregulated TNF production (particularly TNFα) has been implicated in mediating or exacerbating a number of diseases, and it is believed that TNF can cause or contribute to the effects of inflammation in general. IL-8 is a chemotactic factor produced by several cell types including mononuclear cells, fibroblasts, endothelial cells, and keratinocytes. Its production from endothelial cells is induced by IL-1, TNF, or lipopolysaccharide (LPS). IL-8 stimulates a number of functions in vitro. It has been shown to have chemoattractant properties for neutrophils, T-lymphocytes and basophils. Increase in IL-8 production is also responsible for chemotaxis of neutrophils into the inflammatory site in vivo.
Inhibition of signal transduction via p38, which in addition to IL-1, TNF and IL-8 described above is also required for the synthesis and/or action of several additional pro-inflammatory proteins (e.g., IL-6, GM-CSF, COX-2, collagenase and stromelysin), is expected to be a highly effective mechanism for regulating the excessive and destructive activation of the immune system. This expectation is supported by the potent and diverse anti-inflammatory activities described for p38 kinase inhibitors (see Badger et al., J. Pharm. Exp. Thera., 1996, 279, 1453-1461; Griswold et al, Pharmacol. Comm., 1996, 7, 323-229, which are incorporated herein by reference in their entireties). In particular, p38 kinase inhibitors have been described as potential agents for treating rheumatoid arthritis. In addition to the links between p38 activation and chronic inflammation and arthritis, there is also data implicating a role for p38 in the pathogenesis of airway diseases in particular COPD and asthma. Stress stimuli (including tobacco smoke, infections or oxidative products) can cause inflammation within the lung environment. Inhibitors of p38 have been shown to inhibit LPS and ovalbumin induced airway TNF-αIL-1β, IL-6, IL-4, IL-5, and IL-13 (see Haddad et al, Br. J. Pharmacol., 2001, 132 (8), 1715-1724; Underwood et al, Am. J. Physiol. Lung Cell. Mol. 2000, 279, 895-902; Duan et al., 2005 Am. J. Respir. Crit. Care Med., 171, 571-578; Escott et al Br. J. Pharmacol., 2000, 131, 173-176; Underwood et al., J. Pharmacol. Exp. Ther. 2000, 293, 281-288, which are incorporated herein by reference in their entireties). Furthermore, they significantly inhibit neutrophilia and the release of MMP-9 in LPS, ozone or cigarette smoke animal models. There is also a significant body of preclinical data highlighting the potential benefits of inhibition of the p38 kinase that could be relevant in the lung (see Lee et al., Immunopharmacology, 2000, 47, 185-200, which is incorporated herein by reference in its entirety). Thus, therapeutic inhibition of p38 activation may be important in the regulation of airway inflammation.
The implication of the p38MAPK pathway in various diseases has been reviewed by P. Chopra et al. (Expert Opinion on Investigational Drugs, 2008, 17(10), 1411-1425, which is incorporated herein by reference in its entirety).
Known P38 kinase inhibitors have been reviewed by G. J. Hanson (Expert Opinions on Therapeutic Patents, 1997, 7, 729-733) J Hynes et al. (Current Topics in Medicinal Chemistry, 2005, 5, 967-985), C. Dominguez et al (Expert Opinions on Therapeutics Patents, 2005, 15, 801-816) and L. H. Pettus & R. P. Wurtz (Current Topics in Medicinal Chemistry, 2008, 8, 1452-1467), which are incorporated herein by reference in their entireties. P38 kinase inhibitors containing a triazolopyridine motif are known in the art, see for example WO 2007/091152, WO 2004/072072, and WO 2006/018727, which are incorporated herein by reference in their entireties.
International Patent Application WO 2010/094956, which is incorporated herein by reference in its entirety, discloses triazolopyridine derivatives of formula (I) as being p38 MAP Kinase inhibitors:

In such compounds, A represents an optionally substituted divalent arylene radical, an heteroarylene radical, a (C3-C6) divalent cycloalkylene radical having 5 or 6 ring atoms or a pyperidinylene radical. The compounds are said to be useful in as anti-inflammatory agents in the treatment of diseases of the respiratory tract. There remains, however, a need for improved p38 MAP Kinase inhibitors.